This application generally relates to data compression, and more particularly to lossy data compression.
Data compression may be characterized as the process of encoding source information using an encoding scheme into a compressed form having fewer bits than the original or source information. Different encoding schemes may be used in connection with data compression. One class of data compression techniques is generally known as lossless data compression techniques allowing the exact original information to be reconstructed from the compressed form. Such techniques of the first class may be used when it is important that the original and decompressed forms remain identical. Another class of data compression techniques is generally known as lossy data compression techniques in which there is some acceptable loss or difference between the original and decompressed forms. Lossy compression techniques may utilize quality information indicating which portions of the source information are more or less important in comparison to other portions of the source information. The lossy compression techniques may disregard the less important information while still retaining the other more important information. For example, one viewing a picture may not notice the omission of some finer details of the background. The quality information may indicate that the foregoing background details may be less important and such information about the background details may be omitted from the compressed form. In a compression system, an encoder may be used in producing a compressed form of the source and quality information. The compressed form may subsequently be processed by a decoder to form a decompressed reconstruction of the original information.
In order for compressed data communication to work properly, the encoder and decoder have knowledge about the particular encoding scheme used. In existing lossy compression systems, the encoder receives the source information and the quality information and produces an output which compresses the source information as well as describes the quality information. Such existing systems include decoders that may receive the encoded source and quality information in order to render a lossy reconstruction of the source information. In other words, without receiving the quality information, the decoder is unable to decode the compressed form of the source information.
It may be desirable to utilize techniques in which the decoder can decode received compressed input independent of whether the quality information is made available to the decoder.